1. Field of the Invention
This invention relates to a damping mechanism used for preventing, for example, an openable lid from receiving a shock when it is opened or closed and for adjusting the opening/closing speed of the lid.
2. Description of Related Art
For example, a vertically sliding type door is provided in a cup taking-out opening of a coffee vending machine. Such a door is designed to be moved up by hand for opening, and to fall under its own weight for closing when the hand is moved away from the door. If the door falls at extremely high speed to close, the user has to take out the cup while holding the door with his/her hand to keep it from falling.
For this reason, some vending machines use a one-way damper for an opening/closing portion of the door.
The one-way damper has a rotative shaft in a main body thereof. The rotative shaft readily rotates in one direction but has a damping effect in the other direction. As the torque applied in the damping direction increases, the rotational speed can be increased.
The mechanism of such a one-way damper will be explained in brief. A more specific configuration of this is disclosed in, for example, Japanese Patent Publication No. 6-68300.
The one-way damper has a tubular external frame and an inner frame which is built into the external frame and into which a rotative shaft is inserted. Further, the space between the assembled external and inner frames is filled with filler for causing resistance in the production of relative rotation.
On the inner circumference of the inner frame, internal gear teeth are provided, and a plurality of gears are mounted between the internal gear teeth and the above rotative shaft. The inside of the inner frame is configured such that the gears rotate or stop depending on the rotating direction of the rotative shaft.
Therefore, when the rotative shaft is rotated in one direction, the gears in the inner frame are easily rotated along the internal gear teeth, and thus the rotation between the rotative shaft and the inner frame is not interfered with. In other words, the rotative shaft readily rotates in relation to the inner frame, and in this situation, the inner frame and the external frame are integrated.
However, when the rotative shaft is rotated in the other direction, the gears in the inner frame are locked so as to limit the relative rotation of the rotative shaft to the inner frame. In this case, if the applied torque overcomes the resistance between the inner and external frames, the rotative shaft and the inner frame are integrated and rotate relative to the external frame. The resistance between the external frame and the inner frame acts as a brake to exert a damper function.
The following explanation is given for a manner of using the above one-way damper in a door of a vending machine.
A damper body is secured in a main body of the vending machine. A pinion is arranged on the rotative shaft protruding from the damper body, and a rack engaging with the pinion is provided in the door. The rack and the pinion are positioned such that the rack is engaged with the pinion within the range of the vertical movement of the door.
The one-way damper is mounted such that the rotative shaft freely rotates when the door is moved up by hand for opening and the rotative shaft rotates in a direction of limiting the rotation when the door closes. As a result, when the door is moved up, the door can be opened with little resistance, and when the door closes under its own weight, the door falls slowly due to the exerted damper mechanism.
In this way, since the door does not fall immediately after being moved up and opened, it is possible to remove a cup from the vending machine while the hand is moved away from the door.
Using the one-way damper as described above, it is possible to decrease the closing speed of the vertically sliding type door.
Further, it is needed not to allow the door to fall while the cup is being taken out from the coffee vending machine. For this need, a one-way damper capable of allowing a sufficiently large torque for reducing the falling speed is selected.
However, when the above one-way damper is used, the closing speed of the door is constant through all the closing steps. Accordingly, the use of a one-way damper capable of allowing a large torque in order for the door not to close immediately produces the disadvantage that the door does not close for a while after the cup has been taken out.
Again, if the door remains open for a long time, it produces another disadvantage in that it becomes impossible to immediately brew coffee for the next cup and it allows dust to enter the vending machine.
It therefore is an object of the present invention to provide a damping mechanism which is capable of varying the moving speed of an openable door or the like in stages as necessary.
A damping mechanism according to the present invention is featured by including a damper body installed with a damper mechanism and allowing a rotative shaft to protrude therefrom; a plurality of pinions provided on the rotative shaft and each having a different diameter from one another; and a rack member including a plurality of racks respectively engaging with the pinions.
According to the present invention, the moving speed of the door or the like having the damper function is adjusted in a plurality of steps. This allows the door or the like to move at speeds further appropriate to practical use, not at a speed too low or high.